Conventional wind powered aircraft and methods for wind powered flight use a low-speed, high-drag leading aircraft tethered to a low-speed, low-drag trailing aircraft. The low-speed, high-drag leading aircraft remains aloft under a force of lift provided by a high altitude wind acting against the leading aircraft in a flying direction. The low-speed, low-drag trailing aircraft such as a glider is towed at a lower altitude having a lesser wind speed as described in Canadian Patent Application No. 2,296,935.
One of the disadvantages of conventional wind powered aircraft using a low-speed, high-drag leading aircraft tethered to a low-speed, low-drag trailing aircraft can be that the difference in wind speed between the leading aircraft and the trailing aircraft must be as much as 60 miles per hour to remain aloft. Accordingly, aircraft of this configuration cannot operate using winds having lesser differentials which might occur throughout a period of time or occur intermittently during a period of time or occur throughout or intermittently in the flight path of the aircraft. There would be an advantage in a wind powered aircraft which remains aloft even when there are small differences in wind speed between a first altitude and a second altitude or even small differences in wind speed at the same altitude.
An additional disadvantage of conventional wind powered aircraft using a low-speed, high-drag leading aircraft tethered to a low-speed, low-drag trailing aircraft can be that the flying speed of the trailing aircraft to remain aloft must be as much as 40 miles per hour and if the tail wind is 30 miles per hour the trailing aircraft must maintain a ground speed of at least 70 miles per hour. Accordingly, aircraft of this configuration cannot operate using lesser flying speeds which might occur intermittently during a period of time or occur throughout or intermittently in the flight path of the aircraft. There would be an advantage in a wind powered aircraft which remains aloft even when the flying speed is substantially lower than 40 miles per hour or the ground speed is substantially lower than 70 miles per hour.
Another disadvantage of conventional wind powered aircraft using a low-speed, high-drag leading aircraft tethered to a low-speed, low-drag trailing aircraft can be that the vertical separation to achieve sufficient difference in the wind speed to operate requires the use of a correspondingly lengthy tether between the leading aircraft and the trailing air craft. The longer the tether the greater the strength required and the greater the weight to overcome during flight. Additionally, all the components to pay out and take up the tether will be correspondingly larger and have greater weight.
Another disadvantage of conventional wind powered aircraft using a low-speed, high-drag leading aircraft tethered to a low-speed, low-drag trailing aircraft can be substantial wind resistance of the leading aircraft and the trailing aircraft. As an example, an aircraft operating in a wind differential of 60 mph will have wind resistance on the order of 16 times greater than an aircraft operating in a wind differential of 15 mph. Consequently, aircraft operating at a wind differential of 60 must include components having greater strength and greater weight. Also, the strain on components at greater wind differentials can be greater than at lower wind differentials which may lead to shorter life span and higher maintenance of the components and the aircraft.
The instant inventive aircraft affords wind powered flight in a manner which addresses the above-identified disadvantages of conventional wind powered aircraft.